The genus Corymbia is closely related to the genus Eucalyptus, and like Eucalyptus contains tree species that are important for sub-tropical forestry. Corymbia’s close relationship with Eucalyptus suggests genetic studies in Corymbia could benefit from transfer of genetic information from its more intensively studied relatives. Here we report a genetic map for Corymbia spp. based on microsatellite markers identified de novo in Corymbia sp (n=28) or transferred from Eucalyptus (n=117). A comprehensive consensus map was generated from an outbred F2 population created by crossing two Corymbia torelliana x citriodora subsp. variegata F1 trees. The map was composed of 55 microsatellite markers distributed across 12 linkage groups (LOD 3) and had a total length of 417 cM (Kosambi). A high proportion of Eucalyptus microsatellites (63%) transferred to Corymbia allowing a comparative analysis between our Corymbia map and published Eucalyptus maps. Synteny with a Eucalyptus grandis map was moderate and there was no strong evidence for chromosomal structural differences. Instances of non-synteny were associated with large distances on the Eucalyptus map and low power to detect linkage due to low genome coverage in Corymbia. Segregation distortion was primarily restricted to a single linkage group and due to a deficit of hybrid genotypes, suggesting that hybrid inviability shaped the genetic composition of the F2 population in this inter-subgeneric hybrid. The conservation of microsatellite loci and synteny between Corymbia and Eucalyptus suggests there will be substantial value in exchanging information between the two groups.
Shepherd, M, Baker, N, Kasem, S, Lee, D & Henry, RJ 2006, 'Comparative mapping of Eucalyptus and Corymbia', in CF Mercer (ed), Breeding for success: diversity in action: proceedings of the 13th Australasian Plant Breeding Conference, Christchurch, New Zealand, 18-21 April, New Zealand Grassland Association, Dunedin, New Zealand. ISBN: 9780864761678